Dr. Val Arkoosh is the Pennsylvania Senate candidate who is often an afterthought compared to the two front-running Democrats, John Fetterman and Conor Lamb.

But a couple big recent developments — the chance of the Supreme Court sweeping away Roe v. Wade and the entry of Dr. Mehmet Oz into the race’s Republican primary — may give her underdog campaign new momentum.

Dr. Arkoosh, a physician in obstetric anesthesiology and a top elected official in Montgomery County in the Philadelphia suburbs, is trying to pitch herself as a kind of anti-Dr. Oz.

“It really does take a doctor to stand up to a doctor,” Dr. Arkoosh told me. “I don’t even know how he still has a license, with some of the stuff that comes out his mouth,” she said of his promotion of unproved Covid-19 treatments early in the pandemic.

Dr. Oz, a celebrity doctor who, until recently, hosted “The Dr. Oz Show,” is well positioned, thanks to personal wealth and high name recognition, to become a front-runner in a G.O.P. field where no one has yet nailed down voters’ allegiance. The contest to fill Pennsylvania’s open Senate seat will be one of the hardest fought in the country in 2022, with majority control of the Senate at stake.

Dr. Oz, who jumped into the race last week, is framing his candidacy as a conservative’s response to the pandemic, pushing back against mandates, shutdowns and limits to “freedom.”

Dr. Arkoosh, on the other hand, helped lead an aggressive response to the pandemic as the leader of the Montgomery County board of commissioners. In an interview, she contrasted her efforts to ensure the safety of students in her county to Dr. Oz’s position on schools at the time: During the same month that she canceled graduation ceremonies last year, Dr. Oz urged on Fox News that schools should be open because it “may only cost us 2 to 3 percent in terms of total mortality” of the population.

He later said he “misspoke.”

In response to Dr. Arkoosh’s criticism, a spokeswoman for Dr. Oz’s campaign, Erin Perrine, pointed to his success as a heart surgeon and to his TV show and books, which she said “empowered millions to make better health care choices — even if it meant going against the medical establishment.”

Dr. Arkoosh, 61, has struggled for attention from Democratic voters and donors in the shadow of the leaders of her primary: Mr. Fetterman, the lieutenant governor, and Mr. Lamb, a congressman. The two men are usually contrasted against one another as a progressive (Mr. Fetterman, who supported Bernie Sanders in 2016) versus a moderate (Mr. Lamb, who won a congressional district that voted for President Donald J. Trump).

Dr. Arkoosh is liberal on issues — she wants to ban fracking and to add a public option to the health care marketplace — but what sets her apart may be demographics.

Mr. Fetterman and Mr. Lamb are both from Allegheny County in Western Pennsylvania. They each argue that they are best suited to make inroads with white blue-collar voters. Meanwhile, Dr. Arkoosh’s base, Montgomery County — the state’s third most populous and the second richest — is ground zero for the suburban shift to Democrats in recent years. In all, Philadelphia and its suburbs in southeast Pennsylvania contribute 50 percent of the state’s Democratic primary voters.

“In Montgomery County in 2020, we gave President Biden 66,000 more votes than we gave Hillary Clinton,” Dr. Arkoosh said. “It is where my base is, where my strength is.”

Still, J. J. Balaban, a Democratic strategist in Pennsylvania, said that Dr. Arkoosh’s campaign had been underwhelming so far and that she was little known outside Montgomery County.

“It costs a lot of money to get known statewide in Pennsylvania, and she appears to be coming up short,” Mr. Balaban told me. “At the moment, she doesn’t have enough funds to win the Philly market, let alone the state.”

As of October, Dr. Arkoosh had $1 million in her campaign account, which includes a $500,000 personal loan, and she trails Mr. Fetterman’s $4.2 million on hand and Mr. Lamb’s $2.1 million. Her endorsement by Emily’s List, the abortion rights group, did not seem to have boosted her fund-raising much through September.

Even so, the rising prominence of abortion as a potential motivator of Democratic voters in the midterm elections plays to Dr. Arkoosh’s strengths as a doctor. Her specialty means she administers anesthesia to women giving birth and women having abortions.

“As a physician who has sat at the bedside of women who have had to make some of the most difficult decisions of their lives,” she said, “there is no place for any politician in those decisions.”

Arguments before the Supreme Court last week suggested the conservative majority was ready to reverse or severely limit Roe v. Wade in a ruling next year.

“I think this is going to be a very big issue,” Dr. Arkoosh said. “And I think this is going to be an issue that gets women, and particularly suburban women, out in numbers.’’